Compressed gas actuated circuit breaker having a dwell phase in the opening stroke of the movable contact



Dec. 28, 1965 E. FROWEIN ETAL 3,226,513

COMPRESSED GAS ACTUATED CIRCUIT BREAKER HAVING A DWELL PHASE IN THE OPENING STROKE OF THE MOVABLE CONTACT Filed 00tl6, 1963 INVENTORS 16 21 Egberfius Fraulein 5awislas RuFfLeux BY AW, 1% x [MM ATTORNEYS United States Patent 3 226 513 COMPRESSED GAS ATUi ATED CERCUIT BREAK- ER HAVEN G A DWELL PHASE IN THE OPENING STRQKE OF THE MOVABLE CONTACT Egbertus Frowein, Nussbaurnen, Aargau, and Stanislas The present invention relates to a switching device for compressed gas actuated circuit breakers operating with a closed gas circuit, in which the are drawn between the fixed and movable contact members of the breaker is quenched by a quenching gas, particularly SP stored in a high pressure chamber within a casing in which the breaker contact members" are also located, the breaker gases being caught up in a lower-pressure chamber following separation of the contact members, and the movable contact member, which is normally biased by a spring into engagement with the stationary contact member, being caused to assume temporarily an optimum quenching position subsequent to separation from the stationary contact member and thereafter being moved further away from the stationary contact member into its final rest position.

A compressed gas actuated circuit breaker using SF as a quenching medium has become known in which the contact members are located in a low pressure container and are actuated mechanically for switching the breaker on and otf. For quenching of the arc during an opening operation of the breaker, the contact members are blasted by the quenching gas via feeder pipe lines from a high pressure gas container located inside or outside of the low pressure container, the release of the gas supply being effected by means of a mechanically actuated blast valve located at a comparatively great distance from the breaker contact members. It is a disadvantage that such long feed lines, acting as dead spaces must first be filled up after opening of the remotely located blast valve before the stream of quenching gas can become effective at the contact members thus resulting in an undesirably long contact interrupting period. A further disadvantage of the prior known circuit breaker construction resides in the fact that the movable contact members carry out their switching out movement in one stroke so that there is no short dwell at one optimum are quenching distance, and the interrupting power of the circuit breaker is thus not fully utilized. This aspect has already been considered in compressed air circuit breakers of open design in that the movable contact member, constructed as a nozzle when breaking, is first caused to quickly complete a partial stroke and is arrested temporarily by a pneumatically operated arresting device in the optimum arc quenching position before a further movement into the final stationary position takes place. With such a design the blast valve is located a good distance from the circuit breaker so that a relatively large number of components is required. Moreover, the breaking period is still comparatively long due to the long air passageways through which the air must travel in order to reach the contact members.

The present invention has for its principal object a simple solution for pressurized gas circuit breakers of the so-called vessel design and having a closed gas circuit in which the aforementioned disadvantages are avoided and moreover has the additional advantage of a short breaking period. In accordance with the invention, the contact members of the breaker include a stationary nozzle contact member and a movable pin type contact member ocated in a high pressure chamber and surrounded by a 3,226,5l3 Patented Dec. 28, 1965 movable blast valve member in the form of a spring loaded sleeve which serves to control admission of pressurized gas within the high pressure chamber to the gap formed between the contact members upon separation thereof. The valve sleeve is integrated structurally with a drive piston guided within a cylinder, and this drive piston, which is hollow, includes on the inside another guide cylinder portion in which is located a piston portion of the movable contact member. The movable contact member also carries'a second, drive piston which also functions as the slidable member 'of a sleeve valve and which, after reaching the optimum quenching position for the contact members, functions to close off a control chamber against the chamber enclosed by the first mentioned cylinder which itself communicates with the high pressure chamber through a lateral opening in the cylinderwall. The drive piston and its blast valve sleeve are actuatedby a pressure differential established between the pressure in the highpressure chamber which is applied to' the outer face of the drive piston and a lower pressure established within the cylinder which is applied to the inner face of the drive piston, this lower pressure being obtained by a lowering of the pressure in the control chamber which is then-in communication with the interior of the cylinder through the then open sleeve valve.

The foregoing objects and' advantages of the invention will become more apparent from the following detailed description of a preferred embodiment and from the accompanying drawing which shows the improved circuit breaker in a longitudinal central section.

With reference now to the drawing, a combined support and partition insulator 1 is shown and which serves to sub-divide the interior of the enclosed circuit breaker vessel, not illustrated in further detail, into a low pressure chamber 24 and a high'pressure chamber 25. Em-

' bedded in the support insulator 1is a circular flange 2 to which a rigid tubular contact carrier 3 is screwed in a pressure-tight manner. Carrier 3 includes at its underface an annular recess within which is seated a packing ringSa which forms a seat for the end of a cylindrical, movable blast valve sleeve member 9. Screwed into the interior of the tubular contact carrier '3 is the stationary contact member 4 of the circuit breaker, this contact member having a nozzle configuration and being'adapted to have pressurized gas passed through it from the high pressure chamber 25 into the low pressure chamber 24 when theco'ntact members are separated.

A cylindrical current conductor sleeve 5 is secured upon the outer periphery of the carrier 3 which is also electrically conductive and is thus placed in electrical contact with the nozzle contact member 4. The support insulator 1 is also provided with a plurality of ribs 1a and these ribs serve to support a ring-shaped piece lb of insulating material to which is secured an annular plate 6 of metal. A cylinder 7 is secured to the lower face of plate-6 in a depending mannerconcentricwith the nozzle contact member 4. Within cylinder 7 is located a slidable "drive pistonS. Upstandingon the upper side of piston 8 is the tubular blast valve member 9 which is made from a suitable insulating material such as a casting resin. Located within the piston 8 which itself is hollow inside and open at the bottom is a guide cylinder 8b which is secured to the cylindrical'part of piston '8 via a plurality of circumferentially spaced ribs 8a.

The pin type movable contact member of the circuit breaker is shown at 10. It has an intermediate piston portion 10a which is slidably mounted in the guide cylinder 8b and an upper part which extends upwardly through an opening in the top wall of drive piston 8 coaxially with the nozzle contact member 4 and through the blast valve sleeve member 9. At the upper end of contact member 10 is a contact cup 11 which engages the outer periphery of contact member 4 as well as an axially movable burner piece 12 which is biased by. a compression spring 13 so as to cause the tip or cap portion of the burner piece to press against the mouth of the nozzle contact membe 4 within the cup 11.

Below the piston portion a are longitudinally extending slots 100 out into the outer surface of the elongated contact member 10. At its lower end, the movable contact member is enlarged to form a cylindrical drive piston 10b which is slidably received within a cylinder portion 14d of a lower guide piece '14 which latter is secured to and also serves as part of the lower end wall'of cylinder 7. The cylindrical portion 14d also possesses lateral openings 14b above drive piston 10b and other lateral openings 14a below drive piston 10b which serve to place the interior of sleeve 7 in communication with control chamber 27a within guide piece 14 when the drive piston part 1012 of the movable contact member 10 occupies its upper contact closed position, which is the position illustrated in the drawing. Also included internally of the guide piece 14 is a guide sleeve part 140 arranged coaxially with the contact member 10 and held in place by ribs 142. Slidable within the guide sleeve 14c is a rod 18 which extends upwardly through the interior of the hollow part of contact member 10, the top end of the rod being screwed into or otherwisesecured fast to the upper solid part of contact member 10. The lower portion of rod 18 extends downwardly through the guide piece 14 and is adapted to be pulled down and thus pull down the movable contact member 10 and cause it to be separated from the nozzle contact member 4. When rod 18 is pulled down, it is held in that position by a locking device, not shown, associated with the control valve, also not illustrated.

Inserted within the guide cylinder part 14d of guide piece 14 is a contact member 16 which engages the inner surface of cylinder 14d and the outersurface of contact pin 10 and serves to transmit current between the movable contact pin 10 and guide piece 14. Moreover, on the upper end face of the guide cylinder part 14d is located a strike ring which serves as a stop for guide cylinder 8b. Located within the guide piece 14 is a packing ring 17 constituting a seat for the lower end of the cylindrical part of drive piston 18b which functions as a valve sleeve. The opening 21 at the lower end of the guide piece is connected in known manner witha control valve, not illustrated.

A re-closing helical spring 19 is located within cylinder 7 and within drive piston 8, this spring having its lower end pressing against the bottom of a circular recess in the interior of the guide part 14 and its upper end pressing upwardly against the ribs 8a of drive piston 8.

A switching-in compression spring 20 surrounds the rod 18 within the pin contact member 10,v the lower end of this spring pressingagainst theupper face of the stationary guide sleeve part 140 while the upper end of the spring bears upwardly against the end wall defining the upper end of the longitudinal opening within the contact member 10. Inserted within the cylinder 7 are a strike ring 22 as well as plates 23. These serve to buff and limit the stroke of drive piston 8.

The guide cylinder 8b encloses a damping chamber 26 below the piston part 10a of the movable contact member 10, and cylinder 7 encloses a chamber part 2712 which communicates with the high pressure chamber only via The control chamber openings 7a in the cylinder wall. 27a is located below drive piston part 1% within the guide piece 14.

The pressurized gas circuit breaker operates in the following manner.

As shown in the drawing, the circuit breaker is in the switched-in position, the contact members 4 and 10 being closed. Above the support insulator 1, i.e., within chamber 24, as well as in the interior of the blast valve sleeve member 9, low gas pressure prevails. Chambers 25, 26, 27a and 27b are filled with gas at high pressure. The current path through the circuit breaker occurs through parts 5, 3, 4, 11, 12, 10, 16 and 14. In order to effect a switching-out operation, the control chamber 27a and therewith also chamber 27b within cylinder 7 which communicate through openings 14a are brought under low pressure through opening 21 which, in a manner already known, leads to a control valve. This produces a pressure differential 011 drive piston 8 and causes it to move downward due to the high gas pressure within chamber 25 which bears against its upper face. The gas blast valve sleeve 9 which is integrated with piston 8 is also caused to move downward separating the end of the latter from its seat against ring 3a and thus opening the blast valve. After a short downward travel of piston 8, the latter comes against the piston part ltla of the movable contact member 10 and hence causes the latter to also move downward, Shortly thereafter, contact cup 11 disengages from the fixed, nozzle contact member 4 which however remains closed temporarily due to the burner piece 12 being pushed upwardly by the force of spring 13, whereby the burner piece 12 takes over the transmission of current through the circuit breaker. In this manner the high pressure gas is already present at the switching point 12-4 before actual separation of the contact members occurs. In the further course of the circuit breaker action, burner piece 12 is taken along in the downward direction, due to the collar 12a at its lower end, by the movable contact member 10. The are now forming between contact member 4 and burner piece 12 is blasted by the pressurized gas which flows in from the high pressure chamber 25 through the open blast valve 9 and passes through the nozzle contact member 4 to the low pressure chamber 24.

The widest opening of the blast valve is reached as soon as drive piston 8, which is damped, strikes against the strike ring 22. The movable contact member 10 which also made this movement due to piston part 10a being taken along by drive piston 8, has thus been brought into the optimum quenching position in which the valve sleeve part 18b closes openings 14a and hence also closes off openings 14b in guide piece 14 above drive piston part 18b is'able to move the contact member 18 further downward against the counter action of the switching-in spring 2h.

As soon as the filling-up of chamber 27b with gas is nearly completed, the blast valve 9 is moved upwards by the reclosing spring 19 pushing upwardly against ribs 8a of drive piston 8, and the blasting period is terminated when the end of valve part 9 is again seated upon the sealing ring 3a. The stationary, lower end position of the movable contact member 10 is reached as soon as the lower cylindrical end of drive piston part 1% contacts the sealing ring 17, thus closing off the control chamber 27a gas-tight against chamber 27b.

In order to execute the final part of the motion freely, the longitudinally extending slots 10c in movable contact member 18 now connect the damper chamber 26 with chamber 271) via a sufficiently large cross section so that piston 18a can move uninhibited within guide cylinder 8b. Rod 18, connected rigidly' with the movable contact member 10, engages a locking device in the switched-oil position associated with the control valve, not illustrated in detail, which prevents unauthorized switching-on of the circuit breaker in case of unintentional penetration of high pressure gas into the control chamber 27a.

For switching on the circuit breaker, high pressure gas is introduced into the control chamber 27a via opening 21 and the control valve whereby simultaneously the above-mentioned locking device is released, thus freeing rod 18 for movement upward. The switching-on spring 20 is thus now able to move rod 18 and hence the movable contact member 10 upwards so as to eifect reengagement with the stationary nozzle contact member 4 via the burner piece 12 and cup 11.

In conclusion, the improved construction in accordance with the invention is not limited to the specific embodiment illustrated. For example, by placing several such circuit units in series, a circuit breaker with multiple power interruption points can be obtained wherein the breaker units can be assembled on each other in either a horizontal or vertical position. Due to the arrangement of the movable parts and packings in the high pressure chamber, they are advantageously shielded from attack by the circuit breaker igases. A further advantage results from the arrangement of the nozzle contact member at the support insulator, thus making for good accessibility of the contact members when inspecting the circuit breaker.

We claim:

'1. In a compressed gas actuated circuit breaker having a closed gas circuit, the combination comprising means providing a high pressure chamber filled with an arc extinguishing gaseous medium such as SP means providin a low pressure chamber separated from said high pressure chamber by a support insulator, a stationary contact member in the form of a nozzle mounted by said support insulator and through which the compressed gas can flow in passing from said high pressure chamber to said low pressure chamber for collection in the latter, a main drive cylinder mounted in said high pressure chamber, the wall of said cylinder being provided with an aperture placing the interior and exterior of said cylinder in communication with each other, a compressed gas actuated hollow drive piston mounted for sliding movement within said drive cylinder, the upper end of said cylinder being open to admit compressed gas from said high pressure chamber to the upper side of said drive piston, a blast valve closing spring biasing said piston to the upper part of said cylinder, said drive piston including therein a guide cylinder which moves with the piston, an elongated movable contact member including an intermediate piston portion slid-able within said guide cylinder and also actuatable downward by said drive piston, an upper portion extending through the upper end of said hollow drive piston for engagement with said nozzle contact member and a lower cylindrical portion having the dual function of a drive piston and a valve sleeve, a blast valve sleeve upstanding on the upper end of said hollow drive piston and surrounding said movable contact memher, said blast valve sleeve being located within said high pressure chamber and being normally engaged with a seat closing off communication between said high pressure chamber and the junction between said normally closed stationary and movable conact members, a guide piece connected to the lower end of said main drive cylinder, said guide piece including an inlet serving to introduce high pressure gas into said main drive cylinder for flow through the wall aperture of the latter in order to fill said high pressure chamber with compressed gas at high pressure, and also alternatively to place the interior of said main drive cylinder in communication with a chamber at a lower pressure, said guide piece also including a stationary guide cylinder extending into said main drive cylinder and which serves to receive and slidably support said lower cylindrical portion of said movable contact member, said stationary guide cylinder including ports in the wall thereof controlled by downward movement of said lower cylindrical portion of said movable contact member to close off communication between the interior of said main drive cylinder and the inlet of said guide piece, a rod secured at one end to said movable contact member and extending downward through said guide piece, said 'rod being movable downwardly with said movable contact member and arranged to be locked in the down position, and a switching-in spring located within said movable contact member and which biases said member in the upward direction to engage said nozzle contact member, whereby upon establishment of a lower gas pressure witldn said main drive cylinder said hollow drive piston is actuated downwardly by the pressure difierential to remove said blast valve sleeve from its seat and said movable contact member is likewise actuated downwardly, said movable contact member being caused to dwell temporarily at an optimum arc quenching position with respect to said stationary contact member from which it is disengaged, said lower cylindrical portion of said movable contact member at said dwell position then functioning as a valve sleeve to close off communication between the interior of said main drive cylinder and the inlet of said guide piece, said dwell position being thereafter maintained until the interior of said main drive cylinder refills with gas to a high pressure inilowing from said high pressure chamber through said Wall aperture and which is then applied to the end wall of the lower cylindrical portion of said movable contact member causing said cyilndrical portion to function as a drive piston and effect further downward movement of said movable contact member to its lowermost position, the refilling of said main drive cylinder also serving to permit said blast valve closing spring to move said main drive piston and said blast valve sleeve upwardly to reclose said blast valve.

2. A compressed gas actuated circuit breaker as defined in claim 1 wherein said support insulator is provided with ribs which support a flange ring on which said main drive cylinder is mounted within said high pressure chamber.

3. A compressed gas actuated circuit breaker as defined in claim 1 wherein said rod secured to said movable contact member is lockable in the downmost position of said movable contact member to prevent accidental reclosure of said contact members.

4. A compressed gas actuated circuit breaker as defined in claim 1 wherein said movable contact member is provided with a contact cup which surrounds said stationary nozzle contact member.

5. A compressed gas actuated circuit breaker as defined in claim 1 wherein said movable contact member is provided with a contact cup surrounding said stationary nozzle contact member, and is further provided with a movable burner piece and spring means biasing the tip of said burner piece into engagement with the mouth portion of said nozzle contact member, said burner piece remaining engaged with said nozzle contact member for a short time following removal of said contact cup from said nozzle contact member upon downward movement of said movable contact member.

6. A compressed gas actuated circuit breaker as defined in claim 1 wherein said guide cylinder for said piston portion of said movable contact member also functions as a damper element for movement of said movable contact member.

7. A compressed gas actuated circuit breaker as defined in claim 6 wherein the peripheral portion of said movable contact member within said guide cylinder is provided with longitudinally extending slots which reach to the exterior of said cylinder for facilitating the final movement of said movable contact member into its lowermost position.

8. A compressed gas actuated circuit breaker as defined in claim 1 wherein the interior of said main drive cylinder is provided with stops for engaging said main drive piston and said guide cylinder, respectively.

9. A compressed gas actuated circuit breaker as defined in claim 1 wherein said stationary guide cylinder of said guide piece encloses spring loaded contact means engageable with said movable contact member for maintaining proper electrical contact between said contact member and said guide piece through which passes the current controlled by the circuit breaker.

N 0 references cited.

BERNARD A GILHEANY, Primary Examiner. 

1. IN A COMPRESSED GAS ACTUATED CIRCUIT BREAKER HAVING A CLOSED GAS CIRCUIT, THE COMBINATION COMPRISING MEANS PROVIDING A HIGH PRESSURE CHAMBER FILLED WITH AN ARC EXTINGUISHING GASEOUS MEDIUM SUCH AS SF6, MEANS PROVIDIN A LOW PRESSURE CHAMBER SEPARATED FROM SAID HIGH PRESSURE CHAMBER BY A SUPPORT INSULATOR, A STATIONARY CONTACT MEMBER IN THE FORM OF A NOZZLE MOUNTED BY SAID SUPPORT INSULATOR AND THROUGH WHICH THE COMPRESSED GAS CAN FLOW IN PASSING FROM SAID HIGH PRESSURE CHAMBER TO SAID LOW PRESSURE CHAMBER FOR COLLECTION IN THE LATTER, A MAIN DRIVE CYLINDER MOUNTED IN SAID HIGH PRESSURE CHAMBER, THE WALL OF SAID CYLINDER BEING PROVIDED WITH AN APERTURE PLACING THE INTERIOR AND EXTERIOR OF SAID CYLINDER IN COMMUNICATION WITH EACH OTHER, A COMPRESSED GAS ACTUATED HOLLOW DRIVE PISTON MOUNTED FOR SLIDING MOVEMENT WITHIN SAID DRIVE CYLINDER, THE UPPER END OF SAID CYLINDER BEING OPEN TO ADMIT COMPRESSED GAS FROM SAID HIGH PRESSURE CHAMBER TO THE UPPER SIDE OF SAID DRIVE PISTON, A BLAST VALVE CLOSING SPRING BIASING SAID PISTON TO THE UPPER PART OF SAID CYLINDER, SAID DRIVE PISTON INCLUDING THEREIN A GUIDE CYLINDER WHICH MOVES WITH THE PISTON, AN ELONGATED MOVABLE CONTACT MEMBER INCLUDING AN INTERMEDIATE PISTON PORTION SLIDABLE WITHIN SAID GUIDE CYLINDER AND ALSO ACTUATABLE DOWNWARD BY SAID DRIVE PISTON, AN UPPER PORTION EXTENDING THROUGH THE UPPER END OF SAID HOLLOW DRIVE PISTON FOR ENGAGEMENT WITH SAID NOZZLE CONTACT MEMBER AND A LOWER CYLINDRICAL PORTION HAVING THE DUAL FUNCTION OF A DRIVE PISTON AND A VALVE SLEEVE, A BLAST VALVE SLEEVE UPSTANDING ON THE UPPER END OF SAID HOLLOW DRIVE PISTON AND SURROUNDING SAID MOVABLE CONTACT MEMBER, SAID BLAST VALVE SLEEVE BEING LOCATED WITHIN SAID HIGH PRESSURE CHAMBER AND BEING NORMALLY ENGAGED WITH A SEAT CLOSING OFF COMMUNICATION BETWEEN SAID HIGH PRESSURE CHAMBER AND THE JUNCTION BETWEEN SAID NORMALLY CLOSED STATIONARY AND MOVABLE CONACT MEMBERS, A GUIDE PIECE CONNECTED TO THE LOWER END OF SAID MAIN DRIVE CYLINDER, SAID GUIDE PIECE INCLUDING AN INLET SERVING TO INTRODUCE HIGH PRESSURE GAS INTO SAID MAIN DRIVE CYLINDER FOR FLOW THROUGH THE WALL APERTURE OF THE LATTER IN ORDER TO FILL SAID HIGH PRESSURE CHAMBER WITH COMPRESSED GAS AT HIGH PRESSURE, AND ALSO ALTERNATIVELY TO PLACE THE INTERIOR OF SAID MAIN DRIVE CYLINDER IN COMMUNICATION WITH A CHAMBER AT A LOWER PRESSURE, SAID GUIDE PIECE ALSO INCLUD- 